The protein kinases represent a large family of proteins that play a central role in the regulation of a wide variety of cellular processes and maintenance of cellular function. A partial, non-limiting, list of these kinases include: non-receptor tyrosine kinases such as the Tec family (BTK, ITK, Tec, ETK/BMX & RLK/TXK), Janus kinase family (Jak1, Jak2, Jak3 and Tyk2); the fusion kinases, such as BCR-Abl, focal adhesion kinase (FAK), Fes, Lck and Syk; receptor tyrosine kinases such as colony stimulating factor 1 receptor (CSF-1R), epidermal growth factor receptor (EGFR), the platelet-derived growth factor receptor kinase (PDGF-R), the receptor kinase for stem cell factor, c-kit, the hepatocyte growth factor receptor, c-Met, and the fibroblast growth factor receptor, FGFR3; and serine/threonine kinases such as b-RAF, mitogen-activated protein kinases (e.g., MKK6) and SAPK2β. Aberrant kinase activity has been observed in many disease states including benign and malignant proliferative disorders as well as diseases resulting from inappropriate activation of the immune and nervous systems. The novel compounds of this invention inhibit the activity of one or more protein kinases and are, therefore, expected to be useful in the treatment of kinase-mediated diseases.
Bruton's tyrosine kinase (BTK) is a non-receptor tyrosine kinase with a key role in immunoreceptor signaling (BCR, FcεR, FcγR, DAP12, Dectin-1, GPVI etc) in a host of hematopoietic cells including B cells, platelets, mast cells, basophils, eosinophils, macrophages and neutrophils as well as osteoclasts involved in bone destruction (for reviews, see Brunner et al., 2005 Histol. Histopathol., 20:945, Mohamed et al., 2009 Immunol. Rev., 228:58). Mutations in BTK are known to lead to X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice, which are characterized by limited B-cell production & reduced antibody titers (Lindvall et al., 2005 Immunol. Rev., 203:200). The combined action of BTK in multiple cell types makes it an attractive target for autoimmune disease. BTK is related with sequence homology to other Tec family kinases (ITK, Tec, ETK/BMX & RLK/TXK).
In B-lymphocytes, BTK is required for B-cell development and for Ca2+ mobilization following of B-cell receptor (BCR) engagement (Khan et al., 1995 Immunity 3:283; Genevier et al., 1997 Clin. Exp. Immun., 110:286) where it is believed to downstream of Src family kinases (such as Lyn), Syk & PI3K. BTK has been shown to be important for both thymus-dependent and thymus-independent type 2 responses to antigens (Khan et al., Immunity 1995; 3; 283). In mast cells, studies using BTK mouse knock-outs (Hata et al., 1998 J. Exp. Med., 187:1235; Schmidt et al., 2009 Eur. J. Immun., 39:3228) indicate a role for BTK in FcεRI induced signaling, histamine release & production of cytokines such as TNF, IL-2, & IL-4. In platelets, BTK is important for signaling through the glycoprotein VI (GPVI) receptor that responds to collagen and has been shown to promote platelet aggregation and contribute to cytokine production from fibroblast-like synoviocytes (Hsu et al., 2013 Immun. Letters, 150:97). In monocytes and macrophages, the action of BTK in invoked in FcγRI induced signaling and may also have role in Toll-Like Receptor-induced cytokine responses including TLR2, TLR4, TLR8 & TLR9 (Horwood et al., 2003 J. Exp. Med., 197:1603; Horwood et al., 2006 J. Immunol., 176:3635; Perez de Diego et al., 2006 Allerg. Clin. Imm., 117:1462; Doyle et al., 2007 J. Biol. Chem., 282:36959, Hasan et al., 2007 Immunology, 123:239; Sochorava et al., 2007 Blood, 109:2553; Lee et al., 2008, J. Biol. Chem., 283:11189).
Therefore, inhibition of BTK is expected to intervene at several critical junctions of the inflammatory reactions resulting in an effective suppression of autoimmune response. As such diseases involving B-cell receptor activation, antibody-Fc receptor interactions & GPVI receptor signaling may be modulated by treatment with BTK inhibitors. BTK inhibition is likely to act on both the initiation of autoimmune disease by blocking BCR signaling and the effector phase by abrogation of FcR signaling on macrophages, neutrophils, basophils, and mast cells. Furthermore, blocking BTK would provide additional benefit via inhibition of osteoclast maturation and therefore attenuate the bone erosions & overall joint destruction associated with rheumatoid arthritis. Inhibiting BTK may be useful in treating a host of inflammatory and allergic diseases—for example (but not limited to), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS) and type I hypersensitivity reactions such as allergic rhinitis, allergic conjunctivitis, atopic dermatitis, allergic asthma and systemic anaphylaxis. For a review on targeting BTK as a treatment for inflammatory disorders and autoimmunity as well as leukemias and lymphomas, see Uckun & Qazi, 2010 Expert Opin. Ther. Pat., 20:1457. Because BTK is highly expressed in cancers of the hematopoietic system & BTK-dependent signaling in believed to be disregulated there, BTK inhibitors are expected to be useful treatments for B-cell lymphomas/leukemias & other oncologic disease—for example (but not limited to) acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), non-Hodgkin's lymphoma (NHL), small lymphocytic lymphoma (SLL), and acute myeloid leukemia (for review, see Buggy & Elias 2012 Int Rev Immunol. 31:119). Taken together, BTK inhibitors provide a strong method to treat a host of inflammatory diseases and immunological disorders as well as hematologic cancers.
Colony stimulating factor 1 receptor (CSF-1R) is a homodimeric, class III receptor tyrosine kinase that is encoded by the FMS proto-oncogene. It is a 972 amino acid transmembrane protein characterized by an extracellular ligand-binding domain, a single transmembrane domain (TM) a juxtamembrane domain (JM), two intracellular kinase domains (TK1 and TK2), divided by a kinase insert domain (KI), and a c-Terminal domain, UniProt Entry P07333 (Patel et al 2009 Current Topics in Medicinal Chemistry 9:599). Binding of CSF-1 to the extracellular domain of CSF-1R stabilizes receptor dimerization, induces trans-autophosphorylation of the intracellular domain, and activates downstream cytoplasmic signaling. Small molecule inhibitors of CSF-1R active site block receptor autophosphorylation and subsequently block the signals that control the survival, expression, proliferation and differentiation of macrophages.
CSF-1R regulates monocyte survival, proliferation and differentiation as well as macrophage migration (Pixley et al 2004 TRENDS in Cell Biology, 14:628). The natural ligands for CSF-1R have been identified as CSF-1 and IL-34. CSF-1R is expressed in myelomonocytic lineage cell, including hemopoietic progenitors, tissue macrophages, immature B cells, which are implicated in RA pathogenesis (Hamilton 2008 Nature Reviews Immunology 8:533). Activation of CSF-1R is known to play a role in a number of diseases including, but not limited to, RA, Chrohn's disease, ulcerative colitis, ankylosing spondylitis and cancer (Toh et al 2014 Arthritis & Rheumatology 66:2989: Hume et al 2012 Blood 119:1810 and Campbell et al 2000 Journal of Leukocyte Biology 68:144). The natural ligands, CSF-1 and IL-34, are highly expressed in the synovial membrane of RA patients, and CSF-1 levels are increased in the serum and synovial fluid of RA patients and associated with disease activity (Firestein et al 1988 Journal of Experimental Medicine 168:1573; Kawaji et al 1995 Nippon Ika Daigaku Zasshi 62:260; Ritchlin et al 1994 Scand. J. Immunol. 40:292; Takei et al 2000 J. Rheumatol. 27:894; Hwang et al 2012 Arthritis Research & Therapy 14:R14 and Chemel et al 2012 Ann. Rheum. Dis. 71:150).
Monocytes derived from RA patients express elevated levels of FcγR I, IIa and IIIa, increased CD14 and oxygen radicals, and reduced HLA-DR (Shinohara et al 1992 J. Rheumatol. 19:211). This monocyte phenotype can be produced in vitro and in vivo with recombinant CSF-1 (Weiner et al 1994 Cancer Res. 54:4084). Therefore, CSF-1 may drive the recruitment, differentiation and survival of RA synovial macrophages, and in the local proliferation of myeloid progenitors. Further, CSF-1 primes macrophages for greater expression of TNF and other cytokines (Hanamura 1997 Immunopharmacology 37:15). It has been proposed that CSF-1R is involved in a positive feedback loop for chronic inflammation where macrophages secrete TNF and IL-1 that induce stromal cell expression of CSF-1, leading to further expansion of macrophages and additional expression of TNF and IL-1 (Hamilton 1993 Lancet 342:536).
CSF-1 deficient mice have been reported to be resistant to collagen induced arthritis and in a murine model of CIA, CSF-1 was shown to exacerbate disease while the neutralizing anti-CSF-1 antibody ameliorated disease (Campbell et al 2000 Journal of Leukocyte Biology 68:144). An anti-CSF-1R monoclonal antibody was also shown to be efficacious in 2 different animal models for RA (Toh et al 2014 Arthritis & Rheumatology 66:2989). Small molecule inhibitor, GW2580, has been shown to inhibit LPS-induced TNF production in mice (Conway et al 2005 PNAS 102:16078). Additionally, there are several reports of non-selective small molecule CSF-1R inhibitors that have shown efficacy in preclinical disease models for arthritis (Paniagua et al 2006 J. Clin. Invest. 116:2633; Conway et al 2008 J. Pharmacol. Exp. Ther. 326:41; Ohno et al 2008 Eur. J. Immunol. 38:283; Paniagua et al 2010 Arthritis Res. Ther. 12:R32 and Madan et al 2012 J. Imuunol. 189:4123).
Tumor associated macrophages have been associated with poor prognosis in various cancers and are involved in the promotion of angiogenesis, invasion and metastasis (Bingle et al 2002 J. Pathol. 196:254; Pollard 2004 Nat. Rev. Cancer 4:71 and Lewis et al 2006 Cancer Res. 66:605). CSF-1 deficient mice with MMTV-PyMT transgenic tumors exhibited decreased macrophage recruitment and a decreased rate of tumor progression to metastasis (Lewis et al 2006 Cancer Res. 66:605). Mammary epithelial expression of CSF-1 was shown to restore macrophage infiltration and metastatic tumor vasculature was characterized, and the induction of vasculature, was shown to be regulated by Tumor-associated macrophages (TAMs) (Lin et al 2001 J. Exp. Med. 193:727). Human mammary tumor xenografts in mice with CSF-1 antisense oligonucleotide (ODN-196) or small interfering RNAs CSF-1 siRNA and FMS siRNA) down-regulated target proteins and suppressed mammary tumor growth (Biswas et al 2008 J. Immunol. 180:2011). Expression of FMS in breast cancer has been linked to poor survivability and increased tumor size (Kluger et al 2004 Clin. Cancer Res. 10:173; Lin et al 2001 J. Exp. Med. 193:727; Yee et al 2000 Anticancer Res. 20:4379).
CSF-1 antibodies have shown therapeutic potential in treating solid tumors. Treatment with Anti-CSF01 Fab antibody in an MCF-7 mammary xenograft mouse model suppressed tumor growth (Paulus et al 2006 Cancer Res. 66:4349). A small molecule inhibitor, Ki20227, of CSF-1R suppressed osteolytic bone destruction in a metastasis model (Ohno 2006 Mol. Cancer Ther. 5:2634). In a separate study, CSF-1 production was also shown to contribute to osteoclastogenesis from TAMs and to tumor-associated osteolysis (Yang 2002 J. Bone Joint Surg. Br. 84:452).
Therefore inhibition of CSF-1 might be of therapeutic value in treatment of autoimmune diseases and cancer.